1. Technical Field
The present invention relates to a semiconductor device and an oscillation suppressing device.
2. Related Art
As an example of semiconductor devices, a switch device which is configured by connecting a rectifier element such as schottky barrier diodes (SBDs) and the like in anti-parallel to a switch element such as insulated gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs) and the like or a device which is configured by serially connecting two of the switch devices is incorporated in a power conversion system such as power conditioning systems (PCSs), inverters, and smart grids. In these systems, during turn-ons or turn-offs of the switch elements in the semiconductor device or during reverse recovery of the rectifier elements, sudden current changes (di/dt) may cause surge voltage (Ldi/dt) in a wiring inductance (L) in the device resulting in leakage of high frequency noise such as, for example, 10 kHz or less into the other devices in the system.
As such, Patent Document 1, for example, discloses a semiconductor device in which a snubber circuit is connected between two terminals electrically connected to the main circuit in the semiconductor device and exposed to the exterior. For the snubber circuit, an RC snubber which is configured by serially connecting a resistor element and a capacitor element is adopted. The RC snubber can absorb high frequency noise due to surge voltage thus preventing the leakage to the outside of the device.
[Patent Document] Patent Document 1: Japanese Patent Application Publication No. 2014-128066
In recent years, power semiconductor devices (hereinafter referred to as semiconductor devices for short) incorporating next-generation semiconductor elements such as compound semiconductor elements including silicon carbide (SiC) compound semiconductor elements and the like have been developed. Compared to the conventional silicon (Si) semiconductor elements, the SiC element is more highly pressure-resistant due to its high dielectric breakdown field, and also achieves a higher impurity concentration and a thinner active layer, thus enabling a small semiconductor device capable of operating highly efficiently and fast. However, the ability of such a semiconductor element to operate fast may cause high frequency noise that cannot be solved (or suppressed) by conventional RC snubbers or C snubbers.